12v in '99 Suburban

[StormX]

Hello everyone. I have a '99 Suburban with a 12v.
I have a transmission issue with my baby that I don't know exactly how to fix.
I have had the transmission replaced 3 times in 8yrs.
One place told me that there may be questions about my wiring to my TCC solenoid but nothing else on how to fix it.
When I had the trans rebuilt this last time they would not give me warranty said there as an electrical issue that will cause my Torque Converter to go bad
and that needs to be fixed.
I need help with this if anyone has Ideas. This kind of swap requires shops to know how its done and I run into the problem of a lot shops won't do much with it because of the swap.
Thank you so much in advance

 

[ak diesel driver]

What trans?

 

[StormX]

well... I am going to have to get under it the guy who built said a 47RH one trans shop said 47RE and then another trans shop (the latest one) said a 48RE. I do need to crawl under it to see if I can find it

 

[dbrannon79]

iirc a 47RE and 48RE are Dodge transmissions. tell us a little more details about your rig. what engine and all. also any other details leading up to the issue happening from the beginning.

I suspect you have a 4L60E trans unless it has a 454 gasser or diesel, then you'll have a 4L80E.

 

[StormX]

I have a 5.9 12v Cummins with one of those (identification will come I hope when I crawl under it) the last trans shop told me it was a 48RE both from a 94 Ram 2500 in my 99 Suburban. My original engine in the Suburban was the 454 she is a 2500 also. A guy built it in his garage and did an excellent job. he did mention he put a stronger trans in it cuz he had issues, I am guessing the same ones I am having now. I suspect he may have missed something. the first trans rebuild in 2018 the fly wheel explodes in the trans we had it redone and then it would shift in and out of overdrive had it redone again then the same problem for the third rebuild. that is when the trans shop would not give me a warranty due to an electrical issue is all they told me that I will keep having this problem. now it acts like she doesn't want to move very sluggish when I do get up to speed the in and out of overdrive is happening again.

 

[dbrannon79]

Oh neat, a Cummins swap. Ok. Your thread title went way over my head when I read it, I guess I'm having one of those "DOH" moments LOL.

what ECU system are you using to drive the trans? if factory dodge, and I'm sure others will chime in with more knowledge than me, is the 12v fully mechanical or also needs a ECU to run? I thought the only thing in the ECU was the voltage regulator for the alternator.

What I'm getting at is, can you connect to the ECU and read the live data watching when and if it commands OD and TCC lockup how the trans responds. I would get the wheels up off the ground so you can pay more attention to the scanner and trans and not so much the road.

 

[DieselAmateur]

I know nothing about the auto side of things...but I do know the 5.9 is notorious for eating automatic transmissions. I have a buddy with a first gen 12v and he's put 3 transmissions in it in the 15 years he's owned it...I'm going to help him swap a NV4500 into it sometime in the next year or so.

Not saying you should convert to manual, but to avoid history repeating itself I'd strongly suggest digging into why the auto failures happen and see if you want to/ can afford to go the custom built trans route to fix the source of the issue once and for all.

 

[Will L.]

Filling out the signature line with the rig details would greatly help here. Don’t just type them once in a post- who the signature line makes it pop up on one of your posts. That way is the discussion continues. Everyone can quickly glance at what you have to help with the diagnostics.
Definitely include modifications for power, transmission components and brands they used in the rebuild, etc.
putting together a custom rig is the easy part. Making it last long term reliably takes more knowledge and effort (aka $).

Include how you use it. Hauling kids and groceries/ towing a triple axle toy hauler off road/ off roading hard/ frequent burnouts & related fun. This all matters because how you use it changes things.

 

[WarWagon]

NV4500

It will eat those afterthought OD units too. Many HD MT's to choose from out there. At least try for a NV5600 with the lube mod done to it, but, many better MT choices out there.

If you do something really bad in life after you die you may come back as say Bed Sheets In Las Vegas or a clutch/transmission behind a Cummins Diesel.

it would shift in and out of overdrive

If it's a 4L80E and I would suggest other ECM's for other, like Chrysler transmissions, are programmed the same: It's not actually going in and out of overdrive. Something is slipping... Slipping bad now specifically burning the rebuild up in seconds. The ECM sees this slipping and immediately unlocks the Torque Converter Clutch to save the transmission. Slipping gone so the ECM tries to lock up the TCC again and we have Artificial Stupidity as it tries over and over to get something that can't hold the TQ to do so. This can feel like going in and out of OD.

How fast does it feel like it's shifting?

Flywheel exploding is a new level of FUBAR. You may want a ballistic nylon or Kevlar blanket over the flywheel housing and transmission. Think about where your feet are if parts during an exploding failure, and they will, come through the floorpan.

Don't drive it till it's fixed or your rebuild will be toast if it's slipping.

Where are you located as there may be some better shops that can sort out electrical or other excuses the current shop can't.